Calculate the cross-coefficient of demand (price of 1 product affects Qty of another product). Consumers buy 3 avocados but then buy 4 when the price of chips falls from $5 to $3. It doesn't matter if the difference between Qty is in 2 products - we're just measuring the ratio of change in Price to Qty. Use the same formula. QDA/PDA | 3-4 / 3.5 / $5-$3/$4 | = | 1/3.5 / -2/4 | = a Less than 1 b 1 c More than 1